The present invention relates to a salvage and recycling of thermoplastic, organic materials from hollow containers. Typically, hollow thermoplastic containers are used to contain a variety of fluids, such as, for example, carbonated beverages, various food products, motor oils and lubricants and the like. In many cases, the containers bear externally-disposed paper or metal foil labels which identify the product content of the container.
One method to fabricate such containers from organic thermoplastic materials involves the blow molding of so-called parisons or performs at an elevated temperature into the shape of the final container. One method of blow molding containers involves the placement of paper labels on the inside of the blow mold sections. As the heated preform is expanded into the final container shape, it contracts and adheres to the paper label disposed on the internal surface of a mold section. This process, known as in-mold labeling, provides a labeled container in a simplified process compared to more conventional methods of container formation wherein labels are applied after the bottle has been blow molded.
When containers are formed with the label attached thereto inside the mold, the containers are not subject to structural defect inspection prior to labeling. Accordingly, when in-mold labeled containers bear a surface defect, bubble, crack or similar defect which effects the container, there is no opportunity to collect plastic containers without labels for recycling. Typically, unlabeled blow molded containers can be inspected immediately following the blow molding step and defective containers may be reground into granular scrap. Such granular scrap can be reprocessed into new containers.
In-mold label containers which are defective may be recycled into new containers by practicing the process of the present invention.
In the past, many methods for recycling plastics have been disclosed.
For example, U.S. Pat. No. 4,073,661 discloses a continuous process for cleaning soiled plastic material wherein the soiled plastic material is washed in a zone of high turbulence, transferred to a turbulence-free zone, and is thereafter forced under a submerged edge and separated thereby from the impurity which contaminated it initially.
U.S. Pat. No. 3,843,060 discloses a cyclone-type particle separator device which operates to separate a mixture of thermoplastic resin and an associated fabric backing material. The plastic material is granulated and fed into a first separation phase. In the first separation phase, most of the lint and fly is separated from the mixture. The mixture is then fed into a specific gravity air separator which effects a further separation of fiber material from plastic granular material.
U.S. Pat. No. 3,387,793 discloses a method to separate rubber chunks from imbedded foreign objects therein. The chunks of rubber are shredded, subsequently fed into a washing liquid which releases foreign particles from the rubber. The rubber floats to the surface of the washing solution, is collected, and pressed together under ever-increasing pressures to remove a high percentage of the liquid therefrom.
U.S. Pat. No. 2,879,005 discloses a process to recycle scrap plastic wherein the scrap plastic is chopped into small pieces, the small pieces are frozen to enbrittle the plastic, and thereafter subjected to highspeed pulverization to free the impurities from the interior portions of the plastic. Subsequently, the plastic and impurities are separated.
U.S. Pat. No. 4,000,031 describes a process to recover cellulosic fibers and plastic materials from plastic-coated paper and wood. The material is wet-pulped in a water suspension and subsequently discharged into a dilution tank. In the dilution tank, some plastic floats free to the surface and is recovered mechanically. The fiber suspension is screened in a rotating screen-type separator to recover fiberous portions of the mixture.
U.S. Pat. No. 4,034,033 discloses a process to recover material from the center portions of labeled phonograph records. The method to recycle the labeled center portions of the record includes the steps of removing the paper labels from the center of the record disk by immersing that portion of the disk in an aromatic hydrocarbon solution to remove the label. Subsequently, the center portion of the disk is crushed, briquetted with virgin plastic, to achieve a proper regrind proportion, and thermally conditioned to achieve uniform mixing of the regrind and virgin material fractions.
U.S. Pat. No. 4,033,804 describes a method to reclaim thermoplastic material from molecularly-oriented containers by warming the containers so that they shrink a sufficient amount to cause separation of the label from the container.
U.S. Pat. No. 4,067,826 discloses a process for recovering mixed plastic material by a ballistic separation method.